Propulsion aid

Abstract

A propulsion apparatus ( 20 ) which can be mounted to a wheel ( 8 ) (or integrally formed therewith) of a vehicle, for example a wheelchair. The propulsion apparatus ( 20 ) has a first portion which can be statically attached to either a rim of the wheel ( 8 ) or structural member which is rigidly attached to the wheel ( 8 ) projects therefrom. The propulsion apparatus ( 20 ) also has a second portion ( 23 ), which is pivotal about the rotational axis of the wheel ( 8 ). Furthermore, the propulsion apparatus ( 20 ) comprises coupling means which are interposed between the first and second portions so that when the second portion ( 23 ) is rotated about the axis of the wheel ( 8 ) it causes the first portion, and therefore also the wheel ( 8 ), to rotate.

1. A propulsion apparatus mountable to a vehicle, the vehicle comprising at least one ground engaging wheel having an axis of rotation and the propulsion apparatus comprising;
 a hub portion adapted to be statically attached at a location remote from said axis to at least one of a rim of said wheel and a structural member projecting from a plane defined by said wheel, the structural member being rigidly attached to the wheel; 
 a lever arm pivotal about an axis coincident with said rotational axis of said wheel; and 
 a drive mechanism interposed between said hub portion and lever arm such that pivotal movement of said lever arm about said axis causes said hub portion to rotate thereby propelling the vehicle; 
 wherein said hub portion carries means for location of said lever arm such that the axis of rotation of the lever arm is coincident with the axis of the wheel. 
 
   
   
     2. A propulsion apparatus as claimed in  claim 1 , wherein either said hub portion or said lever arm has a continuous contact surface and said drive mechanism is carried by either the hub portion or the lever arm, said drive mechanism being selectively engageable with said continuous contact surface such that, when engaged, pivotal movement of the lever arm about said axis causes said hub portion to rotate thereby propelling the vehicle. 
   
   
     3. A propulsion apparatus as claimed in  claim 2 , wherein the drive mechanism comprises rolling support means adapted to frictionally engage the continuous contact surface. 
   
   
     4. A propulsion apparatus as claimed in  claim 3 , wherein, when the lever arm is pivoted about said axis in a first direction, the rolling support means is selectable to frictionally engage the continuous contact surface to cause the rotation of the hub portion in one sense and, when the lever arm is pivoted about said axis in a second direction, opposite to said first direction, the rolling support means is selectable frictionally engage the continuous contact surface and cause the rotation of the hub portion in an opposite sense. 
   
   
     5. A propulsion apparatus as claimed in  claim 1 , wherein said lever arm comprises a handle, the handle being pivotable about an axis transverse to a longitudinal axis of the lever arm, so as to provide an ergonomic hand movement for a user. 
   
   
     6. A propulsion apparatus as claimed in  claim 5 , wherein the handle comprises an arcuate housing fixedly attached to one end of the lever arm and a D-shaped grip comprising an arcuate portion slidably received within the arcuate housing and a grip portion external of the arcuate housing and interconnecting opposite ends of the arcuate portion. 
   
   
     7. A propulsion apparatus as claimed in  claim 5 , wherein said handle rotates inwardly to provide a means of selectively engaging and disengaging said drive mechanism. 
   
   
     8. A propulsion apparatus as claimed in  claim 1 , wherein said hub portion is statically attached to said wheel at discrete locations. 
   
   
     9. A propulsion apparatus as claimed in  claim 8 , wherein said hub portion is statically attached to said wheel by a plurality of attachment spokes, said attachment spokes being radially extendable from a central hub. 
   
   
     10. A propulsion apparatus as claimed in  claim 9 , wherein said attachment spokes are provided at an end remote from said central hub with a respective channel shaped member adapted to at least partially receive at least one of said rim and said structural member. 
   
   
     11. A propulsion apparatus as claimed in  claim 10  wherein said channel shaped members include a deformable insert adapted to conform under compression to the shape of at least one of said rim and said structural member. 
   
   
     12. A propulsion apparatus as claimed in  claim 11 , wherein said deformable insert is formed of a high friction material. 
   
   
     13. A propulsion apparatus as claimed in  claim 9 , wherein said attachment spokes are pivotally connected at a radially inner end to a respective intermediate member and said intermediate members are pivotally connected to a hub mounted actuating member at circumferentially spaced locations, the attachment spokes being constrained for radial motion such that rotation of the actuating member causes the attachment spokes to extend or retract depending on the sense of the rotation. 
   
   
     14. A propulsion apparatus as claimed in  claim 13 , wherein the extent of rotation of the actuating member is limited by the engagement of a projection within a slot. 
   
   
     15. A propulsion apparatus as claimed in  claim 13 , wherein in moving the attachment spokes from a retracted position to a fully extended position the location at which each intermediate member is pivotally connected to the actuating member moves circumferentially past the location at which the same intermediate member is pivotally connected to the associated attachment spoke such that the attachment spokes are retained in the fully extended position by means of an over-centering arrangement. 
   
   
     16. A propulsion apparatus as claimed in  claim 1 , wherein said lever arm is releasably connectable to said hub portion. 
   
   
     17. A propulsion apparatus as claimed in  claim 1 , wherein the drive mechanism comprises a pair of drive surfaces disposed on opposite sides of a pivot such that only one of said drive surfaces may be brought into frictional engagement with the continuous contact surface at a time. 
   
   
     18. A propulsion apparatus as claimed in  claim 17 , wherein as the lever arm is pivoted about said axis, the engagement of one of said pair of drive surfaces with the continuous contact surface causes the rotation of the hub portion in a first sense while the engagement of the other of said pair of drive surfaces with the continuous contact surface causes the rotation of the hub portion in the opposite sense. 
   
   
     19. A propulsion apparatus as claimed in  claim 18 , wherein one of said pair of drive surfaces is biased towards the continuous contact surface in preference to the other, the biased drive surface engaging the continuous contact surface to propel the vehicle in a forward direction upon pivotal movement of the lever arm about said axis. 
   
   
     20. A propulsion apparatus as claimed in  claim 19 , wherein the biasing of said one of said drive surfaces may be overcome by selective manipulation of a handle. 
   
   
     21. A propulsion apparatus as claimed in  claim 20 , wherein said handle is adapted so that said manipulation is by the rotation of said handle about a longitudinal axis of said lever arm. 
   
   
     22. A propulsion apparatus as claimed in  claim 17 , wherein each drive surface is associated with a respective rolling support means, the rolling support means contacting the continuous contact surface when said associated drive surface is in the proximity of the continuous contact surface, the rolling support means and associated drive surface being coupled such that the drive surface frictionally engages with the continuous contact surface when the associated rolling support means is rotated in a first direction and disengages the continuous contact surface when the associated rolling support means is rotated in an opposite direction. 
   
   
     23. A propulsion apparatus as claimed in  claim 17  and comprising a second pair of drive surfaces disposed on opposite sides of a second pivot, the two pairs of drive surfaces being pivotally interconnected so as to form a parallelogram-type mechanism in which diagonally opposite drive surfaces move together into and out of frictional engagement with the continuous contact surface. 
   
   
     24. A propulsion apparatus as claimed in  claim 1  wherein said lever arm comprises at least two parts, at least one of said parts being releasably connectable to said other parts. 
   
   
     25. A propulsion apparatus as claimed in  claim 1  having a variable drive ratio of propulsion speed of the vehicle to power input by a user of said vehicle. 
   
   
     26. A propulsion apparatus as claimed in  claim 1 , wherein said lever arm is adapted to have a working length that is selectively adjustable such that as the working length of the lever arm is adjusted a drive ratio of propulsion speed of the vehicle to power input by a user of said vehicle is varied. 
   
   
     27. A propulsion apparatus as claimed in  claim 26 , wherein at least a part of said lever arm is adapted to collapse telescopically. 
   
   
     28. A propulsion apparatus as claimed in  claim 1 , wherein said lever arm is collapsible from an in use configuration to a stored configuration such that when collapsed said lever arm has a radial extent less than the radius of said wheel. 
   
   
     29. A propulsion apparatus as claimed in  claim 28 , wherein said lever arm further comprises a hinge at a location spaced radially inwardly of the rim of the wheel. 
   
   
     30. A propulsion apparatus as claimed in  claim 1 , wherein said lever arm further comprises a brake, said brake comprising at least one braking surface moveable between an operable position, in which the braking surface engages the continuous contact surface to slow rotation, and an inoperable position, in which the braking surface is not so engaged; and means for selectively moving said braking surface between said operable and inoperable positions. 
   
   
     31. A propulsion apparatus as claimed in  claim 1 , wherein means for activating said brake are provided on a handle of said lever arm. 
   
   
     32. A propulsion apparatus as claimed in  claim 31 , wherein said handle is movable about the axis transverse to the longitudinal axis of the lever arm such that movement of the handle to an activating position provides the means for activating said brake. 
   
   
     33. A propulsion apparatus as claimed in  claim 1 , wherein braking means are provided on said lever arm, said lever arm being inwardly pivotable such that said braking means is brought into contact with at least one of said wheel and said structural member. 
   
   
     34. A vehicle having at least one ground engaging wheel and a propulsion apparatus in accordance with  claim 1 . 
   
   
     35. A vehicle as claimed in  claim 34 , wherein a separate propulsion apparatus is provided on opposite sides of said vehicle. 
   
   
     36. A vehicle as claimed in  claim 35 , wherein said vehicle is a wheelchair. 
   
   
     37. A method of propelling a vehicle, the method comprising the steps of:
 a) providing a propulsion apparatus as claimed in  claim 1 ; 
 b) connecting said propulsion apparatus to said wheel; 
 c) pivoting said second portion of the propulsion apparatus such that said first portion of the propulsion apparatus is rotated, thereby rotating the wheel.